1. Field of the Invention
The present invention relates to a technique for distributing contents which includes, for example, game programs, video signals, image data, sound data, music data, character information or the composition of them.
2. Description of the Related Art
Along with the popularization of the internet, distributing contents to numbers of people is becoming easier. Recently, pay services of distributing contents are implemented actively. However, in the wide-area network like the internet to which general public people can access, piracy and interception of contents arises easily, thus security and copyright of contents cannot be fully protected.
Moreover, when the contents is distributed using pay service, it is difficult to set charge fee properly, because it is hard to figure out how much the paid contents is utilized.
To solve such problems, the techniques for distributing contents were conventionally proposed, which are described below.
(1) Data Communication System (Japan Laid-Open Patent Publication No. 2000-181963: “First Prior Art”)
In this system, an information recording medium storing a data communication program is sold. User buys this information recording medium, and install the data communication program to the user's PC (Personal Computer) to run this program. After that, the communication line between the user's PC and the apparatus holding pay contents is automatically established, and user can obtain any contents through this communication line by request. Thus, distributing pay contents with the security of the contents being maintained can be achieved in a simple manner. Additionally, charging operation etc. can be easily managed.
(2) Information Distributing System (Japan Laid-Open Patent Publication No.11-328850: “Second Prior Art”)
In this system, a first encryption key and contents encrypted using the first encryption key are transmitted from a server to a user terminal (user machine). At the user terminal side, the encrypted contents are decrypted using the first encryption key. At the same time, charging operation of the contents is executed. Furthermore, a code which varied dynamically along with the elapsed time (DA code) is accompanied with the first encryption key. Therefore, it is possible to prevent the incorrect use of contents and to put a predetermined restriction on the use of contents.
(3) System for managing digital contents utilizing digital watermark (Japan Laid-Open Patent Publication No.11-7241: “Third Prior Art”)
In this system, a contents management program is installed to an OS (Operating System) of a user terminal (user machine) and a monitoring program etc. is transmitted from a contents distribution side to the user terminal via a network to monitor utilizing condition of contents. A digital watermark is embedded in the contents, so that when the contents are used incorrectly, utilizing contents is restricted hereafter. And because the invisible digital watermark is embedded in the contents, routes of copying, forwarding contents etc. can be confirmed even if the contents is utilized correctly.
According to these prior arts described above, security of contents themselves is maintained to a certain level, and utilizing condition of contents can be figured out. And, both of the first and second prior arts have an advantage of clarifying charging system.
However, according to the first prior art, the information recording medium per each content is needed to be prepared and sold, and according to the second prior art, managing DA code is bothersome. Consequently, in the first and second prior arts, the problem remains such that these prior arts cause inflation of costs. Additionally, according to the first prior art, one can monitor the utilizing condition of contents only when the contents is distributed.
According to the third prior art, one can monitor the utilizing condition of contents dynamically. However, because the contents management program is installed to the OS of the user terminal, the versatility of the operation of the user terminal may be spoiled. Additionally, the third prior art has a disadvantage that the monitoring program etc. per each kind of contents is needed to be prepared, and that the prepared monitoring program must be transmitted to the distributing destination which is to be identified whenever the program is transmitted.
The ways of distributing contents become more diverse, and contents itself may be created in a wide variety such as program, data and so on. Therefore, it is difficult to monitor the utilizing condition of contents using the conventional uniform technique.
On the other hand, it is reasonable that the contents provider should install the system of monitoring the utilizing condition of contents separately corresponding to demand of the contents.
Therefore, it is a main object of the present invention to provide a system in which the utilizing condition of contents to be distributed can be monitored properly, permanently and at a low cost.